1. Field of the Invention
This invention relates to a method and apparatus for making enlargements from microfilm.
2. Description of the Prior Art
In U.S. Pat. No. 4,750,021, apparatus for printing enlargements from microfilm is described. This apparatus comprises a microfilm reader-printer. This reader-printer apparatus includes means for quickly retrieving a desired image frame stored on say a 16mm microfilm and an optical system for imaging the microfilm image onto a screen during a viewing mode. An electrophotographic reproduction engine is also provided for reproducing enlargements of the microfilm image onto copy sheets such as plain paper. An advantageous feature of this apparatus is that there is the capability for an operator to control reproduction to a selected portion of the image that appears on the viewing screen. Thus, if an image of a projected image frame is of relatively short length it is quite likely that at least a portion of a second image frame will also appear on the screen. The operator can select an image length to be printed by using indicia associated with the screen and suitable buttons to have the reproduction process controlled so that only the image length segment selected for reproduction is reproduced and thereby preclude the reproduction of information on adjacent image frames. Alternatively, the operator can select an automatic operation mode wherein a reproduction of only the image frame is made. However, in order to accomplish this the image frame needs to be positioned with its topmost edge in register with frame registration marks located at the top of the display screen. While automatic means may be provided to locate the image in this position this may be an inconvenience for the operator who prefers, from a comfort point of view, to view the image so that it is properly positioned for his or her best viewing.
U.S. Pat. No. 4,623,935 describes an apparatus and method for electronically scanning an image frame on a microfilm for transmission of the signals used in reproducing the image for copying same. The apparatus scans the image frame and detects the black borders surrounding same. The apparatus then electronically deletes the transmission of signals reproducing the black borders to provide copies without black borders. In this apparatus there is a need for circuitry to perform electronic scanning of an image and its borders for distinguishing image information from border information.
It is therefore an object of the invention to provide an apparatus and method for producing enlargements of images stored on microfilm without having images from more than one image frame appear on an enlargement and without the need for adjustment of the image frame from a position selected by the operator.